Process for the production of a rare earth metal alkoxide

ABSTRACT

A new improved process of producing a rare earth metal alkoxide is now provided, which comprises reacting a rare earth metal carboxylate with an alkali metal alkoxide in an inert organic solvent under anhydrous conditions, and which can be conducted in a facile way and give the desired rare earth metal alkoxide of a high purity in a high yield.

SUMMARY OF THE INVENTION

This invention relates to a process of producing an alkoxide of a rareearth metal which is useful as a starting material for the production ofa rare earth metal oxide. The rare metal oxides are, in turn, useful,for example, as additives for improving the properties of variousceramic products.

BACKGROUND OF THE INVENTION

In the recent years, the electronics industry has gained a greatadvance, and concurrently various kinds of rare earth elements havebecame utilized in a wide variety of applications. Particularly, in thefield of "Fine Ceramics" industry, various kinds of the oxides of rareearth metals have overtaken some important roles. Especially, yttriumoxide is now calling great attentions, because the yttrium oxide can beadmixed with zirconia (i.e., zirconium oxide) for the purpose ofcontrolling the phase-transition of zirconia ceramic products. In theseyears, it has been found that the method of producing the oxides of rareearth metals, including the yttrium oxide, can be carried out byhydrolysis of such an alkoxide of a rare earth metal represented by thefollowing general formula

    M(OR).sub.3                                                (I)

wherein M denotes a rare earth metal element such as scandium, yttrium,lanthanium, cerium, praseodymium, neodymium, samarium, europium,gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium andlutecium; and R denotes an alkyl group, preferably an alkyl groupcontaining 1 to 10 carbon atoms.

In the prior art, different processes of preparing the rare earth metalalkoxide of the general formula (I) which is useful as the intermediatematerials for use in the production of the rare earth metal oxides areknown, including the under-mentioned processes:

(1) A first process comprising reacting anhydrous scandium chloride withdry methanol (see the "Zeitschrift Anorganische und Allgemeine Chemie"325 (1-2) pages 67-71, (1963)).

(2) A second process comprising reacting an anhydrous rare earth metalchloride with an alkali metal alkoxide in an inert, dry organic solvent(see the "Proceeding Nucleus Radiation Chemical Symposium" pages 15-19(1964); the "Chemistry and Industry" page 120 (1963); ditto, Vol. 9,pages 382-383 (1965); ditto, Vol. 32, pages 1379 (1966); the "ChemischeBerichte" Vol. 93, pages 652-657 (1960); the "Inorganic Chemistry" Vol.5(3), pages 342-346 (1966); and U.S. Pat. No. 3278571 specification, and

(3) A third process comprising reacting a rare metal element with analkanol in the presence of mercuric chloride as catalyst (see the"Inorganic Chemistry" Vol. 5(3), pages 342-346 (1966); and U.S. Pat. No.3278571 spec.).

With all the above-mentioned processes of the prior art, however, theseprocesses suffer from such disadvantages that the desired rare earthmetal alkoxides can be obtained only in a poor yield and also containsome quantities of detrimental impurities. Consequently, the rare earthmetal oxide products as obtained from such rare earth metal alkoxides ofa low purity are also containing considerable quantities of theimpurities. It follows that some operations of the purification arerequired in order to yield such a rare earth metal alkoxide product of ahigh purity which can provide a high purity grade of the rare earthmetal oxide products. In the consequence, the cost for the production ofthe rare earth metal alkoxide of a high purity is inevitably expensive,rendering the resultant rare earth metal oxide products expensive, too.The first and second processes of the prior art essentially require thestarting rare earth metal chloride employed should be anhydrous, asotherwise the desired reaction substantially cannot proceed. Besides,amongst the above-mentioned processes of the prior art, the first andsecond processes of the prior art are particularly disadvantageous inthat the anhydrous rare earth metal chlorides employed as the startingmaterial are normally of a very much highly hygroscopic property and arevery difficult to be handled in a large quantity in commercial practice.The above-mentioned second process of the prior art is alsodisadvantageous in that the rare earth metal elements employed as thestarting material are normally very expensive and the necessary reactioncannot be finished without conducting the refluxing of the reactionmixture under heating for a long period of time, so that this process isvery time-consuming and is not suitable as a commercial method which isto be carried out in a large scale. Furthermore, all the first, secondand third processes of the prior art as mentioned above involve the useof the chlorides as the starting material or as the reaction reagent oras the necessary catalyst, and usually a non-neglectable quantity of thechloride anion should necessarily be migrated into the intermediateproducts and even into the final products as the detrimental impuritywhich is very hardly to be eliminated through simple procedures ofpurification. This seems largely due to that a slight quantity of therare earth metal chloride is soluble in organic solvents such asaromatic hydrocarbons, e.g., benzene, toluene and xylene.

In these circumstances, we, the inventors, have made extensiveresearches on the process of producing the rare earth metal alkoxide inan attempt to provide a new improved process which can be free from theaforesaid disadvantages of the prior art processes. As a result, we havenow found that when an anhydrous rare earth metal carboxylate isemployed as the starting material in place of the anhydrous rare earthmetal chloride which had been employed in the prior art processes andwhen this anhydrous rare earth metal carboxylate is reacted with analkali metal alkoxide, there can be produced the rare earth metalalkoxide of a higher purity in a higher yield than by the prior artprocesses and the rare earth metal alkoxide as produced can easily berecovered. On the basis of these findings, we have finished thisinvention.

DETAILED DESCRIPTION OF THE INVENTION

According to this invention, therefore, there is provided a process forthe production of a rare earth metal alkoxide represented by the generalformula

    M(OR).sub.3                                                (I)

wherein M denotes a rare earth metal element and R denotes an alkylgroup, which comprises reacting a rare earth metal carboxylaterepresented by the general formula

    M.sub.n X.sub.3                                            (II)

wherein M is as defined above, X denotes the residue of a carboxylicacid and n is an integer of 1 or 2, provided that n is 1 when X denotesthe residue of a mono-carboxylic acid; and n is 2 when X denotes theresidue of a di-carboxylic acid, with an alkali metal alkoxiderepresented by the general formula

    ROM'                                                       (III)

wherein R is an alkyl group as defined above and M' denotes an alkalimetal, in an inert organic solvent or liquid as the reaction mediumunder the anhydrous conditions.

To depict the differences between the process of this invention and theaforesaid prior art processes, the reactions involved in these processesare shown briefly by the following reaction equations in comparison.##STR1##

According to the process of this invention, it is feasible to produce arare earth metal alkoxide of a high purity in a favorably high yield.The rare earth metal alkoxide of a high purity can be obtained at a lowcost without requiring special purification of the rare earth metalalkoxide. Thus, the process of this invention can afford in a yield of90% or more such a rare earth metal alkoxide product which issubstantially not containing the detrimental impurities therein.Accordingly, it is clear that the process of this invention can provideremarkable improvements in respect of the yield of and purity of theaimed product as well as the simplicity and cost of the process to beoperated, as compared to the aforesaid prior art processes by which onlythe rare earth metal alkoxide containing considerable quantities of theimpurities is afforded in a poor yield.

The process for the production of a rare earth metal alkoxide accordingto this invention is now described in more details. This process can becarried out in a facile way merely by adding a stoichiometrial orsubstantially stoichiometrial quantity of an alkali metal alkoxide ofthe general formula (III) to a solution or suspension of a rare earthmetal carboxylate of the general formula (II) in an inert organicsolvent or liquid and then stirring the resultant admixture for a timeof 1-3 hours at such a temperature which may range from ambienttemperature to the refluxing temperature of the solvent employed. Thereaction of the alkali metal alkoxide with the rare earth metalcarboxylate is necessary to be conducted under the anhydrous conditions,since the hydrolysis of the resulting rare earth metal alkoxide asproduced can take place if there is present a significant amount ofwater in the reaction system. After the reaction is complete, thereaction mixture is filtered to remove the alkali metal carboxylatewhich is insoluble in and deposited from the reaction medium, and inthis way there is afforded as the filtrate a clear and homogenoussolution of the desired rare earth metal alkoxide in the organicsolvent. It is preferred that the filtrate should be concentrated todryness by evaporation of the solvent and the residue then may beadmixed with a volume of an aromatic hydrocarbon such as benzene,toluene, xylene, for re-dissolution of the rare earth metal alkoxide.The solution so obtained may then be filtered again if there isremaining some insoluble matters comprising the starting rare earthmetal carboxylate which remains unreacted and is substantially insolublein the aromatic hydrocarbon, as well as the by-produced alkali metalcarboxylate which is also insoluble in the aromatic hydrocarbons. Thus,a clear and homogeneous solution of the desired rare earth metalalkoxide is obtained.

The rare earth metal carboxylate (II) which is used as the startingmaterial in the reaction may be the salt of a mono-carboxylic acid ordi-carboxylic acid with the rare earth metal and is supplied in theanhydrous form to the reaction. When a hydrous rare earth metalcarboxylate is dissolved in benzene, toluene, xylene and the resultantsolution is distilled, the water content can conveniently be removed byazeotropic distillation, affording the anhydrous rare earth metalcarboxylate. In general, the rare metal carboxylate (II) may either besuch one of the formula ##STR2## wherein M denotes a rare earth metaland R_(a) denotes a hydrogen atom or an alkyl group of 1 to 10 carbonatoms, or an optionally substituted aryl group such as phenyl and tolyl,or may be such one of the formula ##STR3## wherein M denotes a rareearth metal and R_(b) denotes a chemical linkage bond or an alkylenegroup of 1-4 carbon atoms, such as methylene, and ethylene, or phenylgroup. In the present process, it is preferred to use the formate,acetate, propionate, butyrate, oxalate, malonate, succinate or benzoateof the rare earth metal as the starting material. The rare earth metalformate, acetate, propionate, benzoate and oxalate are most preferred tobe used as the starting material.

In the process of this invention, the rare earth metal carboxylate (II)may be reacted with the alkali metal alkoxide (III) in thestoichiometrical or substantially stoichiometrical proportions, and itis economically preferable to use 3 to 3.3 molar proportions of thealkali metal alkoxide and 0.85 to 5 liters of the organic solvent per 1molar proportion of the anhydrous rare earth metal carboxylate. For thereaction medium in which the present process is carried out, any organicsolvent or liquid in which the starting rare earth metal carboxylate andthe alkali metal alkoxide reagent are soluble or dispersible may beused, as long as the organic solvent or liquid is inert to the reactioninvolved. Alkanols, preferably an alkanol of 1 to 10 carbon atoms, suchas methanol, ethanol, hexanol, octanol and the like are preferred as thereaction medium in view of their high solvent-capacity and their easyhandability. Such aromatic hydrocarbons as benzene, toluene, xylene andthe like may be used as the reaction medium, as both the starting rareearth metal carboxylate and the alkali metal alkoxide reagent are hardlysoluble but easily dispersible in these aromatic hydrocarbons. For asolvent for re-dissolution of the rare earth metal alkoxide product, itis possible to employ any inert organic solvent in which the rare earthmetal alkoxide is soluble. In particular, such aromatic hydrocarbons asbenzene, toluene, xylene and the like may preferably be employed forthis re-dissolution purpose, because such an amount of the starting rareearth metal carboxylate which remains unreacted is not soluble in thesearomatic hydrocarbons and thus is removable by filtration. When sucharomatic hydrocarbon for the re-dissolution purpose is used in a volumeof 0.5 to 5 l per 1 molar proportion of the starting anhydrous rareearth metal carboxylate, this volume of the aromatic hydrocarbon issufficient to re-dissolve the rare earth metal alkoxide product asformed from the starting rare earth metal carboxylate material.

Normally, the rare earth metal alkoxide can readily undergo thehydrolysis even in the presence of a very slight amount of water, andowing to this, the rare earth metal alkoxide may preferably be providedto a subsequent application or processing, while being retained in theform of the solution in the dry organic solvent. If required, however,it is possible to isolate the rare earth metal alkoxide from thesolution by distilling off the solvent and handling the solid residuecarefully under the anhydrous conditions.

In accordance with the process of this invention, the procedure forreacting the rare earth metal carboxylate with the alkali metal alkoxidemay comprise contacting the alkali metal alkoxide reagent immediatelywith the starting rare earth metal carboxylate dissolved or dispersed inan organic solvent or liquid, as shown briefly by the followingequation: ##STR4## where M, M', R, X and n are as defined above.

Thus, in this embodiment of the process of the invention, the alkalimetal alkoxide, either alone or as dissolved or suspended in Solvent 2as an appropriate organic solvent or liquid, may be added to a solutionor suspension of the anhydrous rare earth metal carboxylate dissolved orsuspended in Solvent 1 as an appropriate organic solvent or liquid.Here, Solvent 1 and Solvent 2 may be the same or different and mayindependently be selected from the aromatic hydrocarbons such asbenzene, toluene, xylene and the like, as well as the alkanols such asmethanol, ethanol, butanol, octanol and the like. While, a furtherembodiment of the present process may comprise adding a metallic alkalimetal to a solution of the anhydrous rare earth metal carboxylate in analkanol solvent and thereby reacting the metallic alkali metal with thealkanol as the solvent, so as to form the necessary alkali metalalkoxide reagent in situ in the solution of the rare earth metalcarboxylate, and then allowing the alkali metal alkoxide as formed, tobe reacted in turn, with the rare earth metal carboxylate present in thesolution. This further embodiment of the present process may briefly berepresented by the following equation: ##STR5## where M, R, X and n areas defined above.

Thus, in this further embodiment of the process, an alkali metal in themetallic state may be added to a solution of the starting anhydrous rareearth metal carboxylate in solution in an alkanol solvent of the formulaROH where R is as defined above. This alkanol solvent may either beselected from the alkanols such as methanol, ethanol, n-propanol,isopropanol, n-butanol, tert-butanol, octanol and the like and may beprovided either alone or in mixture with an aromatic hydrocarbon such asbenzene, toluene, xylene and the like. The metallic alkali metal soadded can react with the solvent alkanol to produce the alkali metalalkoxide reagent in situ the solution of the starting rare earth metalcarboxylate.

This invention is now illustrated with the following Examples to whichthis invention is limited in no way.

EXAMPLE 1 Production of yttrium methoxide (according to the firstembodiment for the reaction)

Anhydrous yttrium acetate (8.0 g, 0.03 mol.) and benzene (50 ml) wereplaced in a round-bottomed flask of 100 ml-capacity, to which was thenadded dropwise a methanolic solution of sodium methoxide (containing0.09 mol. of CH₃ ONa at a concentration of 28% by weight) understirring. After the addition of the sodium methoxide, the reactionmixture in the flask was refluxed for 2 hours by heating with aid of amantle heater. The reaction solution was then allowed to cool to ambienttemperature and then filtered to remove the deposited crystals(comprising the unreacted yttrium acetate and the by-produced sodiumacetate). The filtrate obtained was concentrated to dryness byevaporation of the solvent and the residue was taken up into 30 ml ofbenzene added thereto. The resultant solution in benzene was filtered toremove the insoluble solids comprising the unreacted yttrium acetate andthe by-produced sodium acetate, and to give a clear and homogeneoussolution of yttrium methoxide in benzene. This solution in benzene wasconcentrated to dryness by evaporation of the solvent to afford 5.3 g ofyttrium methoxide as a white colored crystals. Yield 96.6%

Elemental analysis: Calcd.: C 19.8%, H 5.0%, O 26.4%, Found: C 19.6%, H5.1%, O 26.1%.

EXAMPLES 2-22

The process of Example 1 was repeated using such different rare earthmetal carboxylates, such different alkali metal alkoxides, and suchdifferent organic solvents (or organic liquid) for the rare earth metalcarboxylate as indicated in Table 1 below, and effecting the reactionaccording to the first embodiment (the first reaction procedure) of thisinvention. The alkali metal alkoxide employed was supplied as a solutionof it in the alkanol from which the alkali metal alkoxide was derived.

                                      TABLE 1                                     __________________________________________________________________________    Rare earth        Alkali                                                                              Re- Re-                                               metal             metal action                                                                            action           Elemental analysis (%)           Carboxylate  Solvent                                                                            alkoxide                                                                            temp.                                                                             time                                                                              Products Yield                                                                             Calcd.   Found                   Ex.                                                                              [g], (mol.)                                                                             (ml) (mol.)                                                                              (°C.)                                                                      (hrs.)                                                                            [g]      (%) C  H  O  C  H  O                 __________________________________________________________________________    2  scandium  toluene                                                                            sodium                                                                              solvent                                                                           3   Sc(OCH.sub.3).sub.3                                                                    91.6                                                                              26.1                                                                             6.5                                                                              34.8                                                                             25.4                                                                             6.8                                                                              33.9                 formate   (50) methoxide                                                                           re-     [3.8]                                            Sc(OCOH).sub.3 (0.09)                                                                              fluxing                                                  [5.4] (0.03)                                                               3  Y(OCOH).sub.3                                                                           toluene                                                                            sodium                                                                              solvent                                                                           "   Y(OCH.sub.3).sub.3                                                                     90.8                                                                              19.8                                                                             4.9                                                                              26.4                                                                             20.1                                                                             5.1                                                                              25.8                 [6.7] (0.03)                                                                            (50) methoxide                                                                           re-     [5.0]                                                           (0.09)                                                                              fluxing                                               4  Pr(OCOH).sub.3                                                                          toluene                                                                            sodium                                                                              solvent                                                                           "   Pr(OCH.sub.3).sub.3                                                                    93.5                                                                              15.4                                                                             3.8                                                                              20.5                                                                             15.6                                                                             3.7                                                                              20.2                 [8.3] (0.03)                                                                            (50) methoxide                                                                           re-     [6.6]                                                           (0.09)                                                                              fluxing                                               5  Nd(OCOH).sub.3                                                                          toluene                                                                            sodium                                                                              solvent                                                                           "   Nd(OCH.sub.3).sub.3                                                                    90.5                                                                              15.2                                                                             3.8                                                                              20.2                                                                             15.6                                                                             3.8                                                                              20.9                 [8.4] (0.03)                                                                            (50) methoxide                                                                           re-     [6.9]                                                           (0.09)                                                                              fluxing                                               6  Sm(OCOH).sub.3                                                                          toluene                                                                            sodium                                                                              solvent                                                                           "   Sm(OCH.sub.3).sub.3                                                                    94.2                                                                              14.8                                                                             3.7                                                                              19.7                                                                             15.2                                                                             3.6                                                                              20.9                 [8.6] (0.03)                                                                            (50) methoxide                                                                           re-     [6.4]                                                           (0.09)                                                                              fluxing                                               7  Dy(OCOH).sub.3                                                                          toluene                                                                            sodium                                                                              solvent                                                                           "   Dy(OCH.sub.3).sub.3                                                                    94.0                                                                              14.1                                                                             3.5                                                                              18.8                                                                             15.1                                                                             3.2                                                                              18.8                 [8.9] (0.03)                                                                            (50) methoxide                                                                           re-     [7.2]                                                           (0.09)                                                                              fluxing                                               8  Yb(OCOH).sub.3                                                                          toluene                                                                            sodium                                                                              solvent                                                                           "   Yb(OCH.sub.3).sub.3                                                                    91.9                                                                              13.5                                                                             3.4                                                                              18.0                                                                             13.5                                                                             3.7                                                                              18.8                 [9.2] (0.03)                                                                            (50) methoxide                                                                           re-     [7.3]                                                           (0.09)                                                                              fluxing                                               9  yttrium   toluene                                                                            lithium                                                                             solvent                                                                           2   Y(Oi-C.sub. 3 H.sub.7).sub.3                                                           97.1                                                                              40.7                                                                             8.0                                                                              18.1                                                                             40.5                                                                             8.2                                                                              18.1                 acetate   (50) iso-  re-     [7.7]                                            Y(OCOCH.sub.3).sub.3                                                                         propoxide                                                                           fluxing                                                  [8.0] (0.03)   (0.09)                                                      10 scandium  xylene                                                                             potassium                                                                           solvent                                                                           "   Sc(O t-C.sub. 7 H.sub.9).sub.3                                                         92.3                                                                              54.5                                                                             10.2                                                                             18.2                                                                             56.1                                                                             10.4                                                                             17.7                 oxalate   (50) tert- re-     [7.3]                                            Sc.sub.2 (C.sub.2 O.sub.4).sub.3                                                             butoxide                                                                            fluxing                                                  [5.3] (0.015)  (0.099)                                                     11 Y.sub.2 (C.sub.2 O.sub.4).sub.3                                                         xylene                                                                             potassium                                                                           solvent                                                                           "   Y(Ot-C.sub. 4 H.sub.9).sub.3                                                           90.8                                                                              46.8                                                                             8.8                                                                              15.6                                                                             46.1                                                                             8.3                                                                              16.6                 [6.6] (0.015)                                                                           (50) tert- re-     [8.4]                                                           butoxide                                                                            fluxing                                                                 (0.099)                                                     12 Dy(C.sub.2 O.sub.4).sub.3                                                               xylene                                                                             potassium                                                                           solvent                                                                           "   Dy(O t-C.sub.4 H.sub.9).sub.3                                                          91.1                                                                              37.7                                                                             7.1                                                                              12.6                                                                             38.2                                                                             7.5                                                                              12.4                 [8.8] (0.015)                                                                           (50) tert- re-     [10.4]                                                          butoxide                                                                            fluxing                                                                 (0.099)                                                     13 Yb.sub.2 (C.sub.2 O.sub.4).sub.3                                                        xylene                                                                             potassium                                                                           solvent                                                                           "   Yb(O t-C.sub.4 H.sub.9).sub.3                                                          91.8                                                                              36.7                                                                             6.9                                                                              12.2                                                                             35.8                                                                             7.1                                                                              11.9                 [9.2] (0.015)                                                                           (50) tert- re-     [10.7]                                                          butoxide                                                                            fluxing                                                                 (0.099)                                                     14 Y(OCOH).sub.3                                                                           benzene                                                                            sodium                                                                              solvent                                                                           3   Y(On-C.sub. 6 H.sub.13).sub.3                                                          92.4                                                                              55.1                                                                             10.0                                                                             12.2                                                                             57.1                                                                             10.6                                                                             11.8                 [6.7] (0.03)                                                                            (50) n-hexyrate                                                                          re-     [10.7]                                                          (0.099)                                                                             fluxing                                               15 Sm(OCOH).sub.3                                                                          benzene                                                                            sodium                                                                              solvent                                                                           "   Sm(On-C.sub. 6 H.sub.13).sub.3                                                         91.1                                                                              47.7                                                                             8.6                                                                              10.6                                                                             47.1                                                                             8.2                                                                              11.3                 [8.6] (0.03)                                                                            (50) n-hexyrate                                                                          re-     [12.4]                                                          (0.099)                                                                             fluxing                                               16 Dy(OCOH).sub.3                                                                          benzene                                                                            sodium                                                                              solvent                                                                           "   Dy(On-C.sub.C.sub.6 H.sub.13).sub.3                                                    90.5                                                                              46.4                                                                             8.5                                                                              10.3                                                                             45.3                                                                             8.8                                                                              10.9                 [8.9] (0.03)                                                                            (50) n-hexyrate                                                                          re-     [12.7]                                                          (0.099)                                                                             fluxing                                               17 Yb(OCOH).sub.3                                                                          benzene                                                                            sodium                                                                              solvent                                                                           "   Yb(On-C.sub. 6 H.sub.13).sub.3                                                         91.1                                                                              45.4                                                                             8.2                                                                              10.1                                                                             45.1                                                                             8.1                                                                              11.1                 [9.2] (0.03)                                                                            (50) n-hexyrate                                                                          re-     [13.0]                                                          (0.099)                                                                             fluxing                                               18 Y(OCOCH.sub.3).sub.3                                                                    benzene                                                                            sodium                                                                              solvent                                                                           1   Y[OCH(C.sub.2 H .sub.5)                                                                95.8                                                                              58.1                                                                             10.4                                                                             11.1                                                                             59.2                                                                             10.1                                                                             11.0                 [8.0] (0.03)                                                                            (50) 3-    re-     n-C.sub.4 H.sub.9 ].sub.3                                       heptyrate                                                                           fluxing [12.6]                                                          (0.099)                                                     19 yttrium   xylene                                                                             lithium                                                                             solvent                                                                           2   Y(On-C.sub. 3 H.sub.7).sub.3                                                           90.8                                                                              40.6                                                                             7.9                                                                              18.1                                                                             40.3                                                                             8.1                                                                              17.6                 benzoate  (50) n-    re-     [7.2]                                             ##STR6##      propoxide (0.099)                                                                   fluxing                                               20                                                                                ##STR7## xylene (50)                                                                        lithium n-                                                                          solvent re-                                                                       "   Gd(On-C.sub. 3 H.sub.7).sub.3 [9.2]                                                    92.4                                                                              32.3                                                                             6.3                                                                              14.4                                                                             32.6                                                                             6.3                                                                              14.1                 [13.71] (0.03) propoxide                                                                           fluxing                                                                 (0.099)                                                       21                                                                              ##STR8## xylene (50)                                                                        lithium n-                                                                          solvent re-                                                                       "   Dy(On-C.sub. 3 H.sub.7).sub.3 [9.2]                                                    90.6                                                                              31.8                                                                             6.2                                                                              14.1                                                                             30.9                                                                             6.4                                                                              14.0                 [13.8] (0.03)  propoxide                                                                           fluxing                                                                 (0.099)                                                       22                                                                              ##STR9## xylene (50)                                                                        lithium n-                                                                           solvent re-                                                                      "   Yb(On-C.sub. 3 H.sub.7).sub.3 [9.6]                                                    91.3                                                                              30.9                                                                             6.0                                                                              13.7                                                                             30.7                                                                             6.1                                                                              14.1                 [14.2] (0.03)  propoxide                                                                           fluxing                                                                 (0.099)                                                     __________________________________________________________________________

EXAMPLE 23 Production of scandium ethoxide (according to the secondembodiment of the process)

Scandium propionate (0.03 mol.), benzene (50 ml) and ethanol (10 ml)were placed in a round-bottomed flask of 100 ml-capacity, to which wasthen added slowly 0.6 g (0.09 mol.) of metallic lithium under stirring.After the addition of the metallic lithium, the admixture in the flaskwas refluxed for 1 hour by heating with aid of a mantle heater, and thenthe reaction solution was processed in the same manner as in Example 1to afford 6.4 g of scandium ethoxide as a white colored crystal. Yield95.6%

Elemental analysis: Calcd.: C 32.2%, H 6.7%, O 21.4%, Found: C 31.8%, H6.7%, O 21.1%.

EXAMPLES 24-55

The process of Example 23 was repeated using such different rare earthmetal carboxylates, such different metallic alkali metals and suchdifferent alkanol solvents as indicated in Table 2 below, and effectingthe reaction according to the second embodiment (the second reactionprocedure) of this invention.

                                      TABLE 2                                     __________________________________________________________________________    Rare earth-               Re- Re-                                             metal                 Alkali                                                                            action                                                                            action         Elemental analysis (%)           Carboxylate Solvent                                                                            Alkanol                                                                            metal                                                                             temp.                                                                             time                                                                              Products                                                                             Yield                                                                             Calcd.   Found                   Ex.                                                                              [g], (mol.)                                                                            (ml) (ml) (mol.)                                                                            (°C.)                                                                      (hrs.)                                                                            [g]    (%) C  H  O  C  H  O                 __________________________________________________________________________    24 lanthanium                                                                             benzene                                                                            ethanol                                                                            lithium                                                                           solvent                                                                           1   La(OC.sub.2 H.sub.5).sub.3                                                           91.6                                                                              26.3                                                                             5.5                                                                              17.5                                                                             26.2                                                                             5.3                                                                              18.2                 propionate                                                                             (50) (10) (0.09)                                                                            re-     [7.5]                                          La(OCOC.sub.2 H.sub.5).sub.3                                                                         fluxing                                                [11.2] (0.03)                                                              25 Ce(OCOC.sub.2 H.sub.5).sub.3                                                           benzene                                                                            ethanol                                                                            lithium                                                                           solvent                                                                           "   Ce(OC.sub.2 H.sub.5).sub.3                                                           93.3                                                                              26.2                                                                             5.5                                                                              17.5                                                                             26.0                                                                             5.3                                                                              17.7                 [12.8] (0.03)                                                                          (50) (10) (0.09)                                                                            re-     [7.7]                                                                 fluxing                                             26 Eu(OCOC.sub.2 H.sub.5).sub.3                                                           benzene                                                                            ethanol                                                                            lithium                                                                           solvent                                                                           "   Eu(OC.sub.2 H.sub.5).sub.3                                                           90.6                                                                              25.1                                                                             5.2                                                                              16.7                                                                             24.4                                                                             5.0                                                                              17.0                 [13.1] (0.03)                                                                          (50) (10) (0.09)                                                                            re-     [7.8]                                                                 fluxing                                             27 Gd(OCOC.sub.2 H.sub.5).sub.3                                                           benzene                                                                            ethanol                                                                            lithium                                                                           solvent                                                                           "   Gd(OC.sub.2 H.sub.5).sub.3                                                           92.2                                                                              24.6                                                                             5.1                                                                              16.4                                                                             24.1                                                                             5.3                                                                              16.0                 [13.3] (0.03)                                                                          (50) (10) (0.09)                                                                            re-     [8.1]                                                                 fluxing                                             28 Tb(OCOC.sub.2 H.sub.5).sub.3                                                           benzene                                                                            ethanol                                                                            lithium                                                                           solvent                                                                           "   Tb(OC.sub.2 H.sub.5).sub.3                                                           93.7                                                                              24.5                                                                             5.1                                                                              16.3                                                                             24.7                                                                             5.5                                                                              17.0                 [13.3] (0.03)                                                                          (50) (10) (0.09)                                                                            re-     [8.3]                                                                 fluxing                                             29 Dy(OCOC.sub.2 H.sub.5).sub.3                                                           benzene                                                                            ethanol                                                                            lithium                                                                           solvent                                                                           "   Dy(OC.sub.2 H.sub.5).sub.3                                                           94.3                                                                              24.2                                                                             5.0                                                                              16.1                                                                             24.7                                                                             5.1                                                                              16.0                 [13.4] (0.03)                                                                          (50) (10) (0.09)                                                                            re-     [8.4]                                                                 fluxing                                             30 Ho(OCOC.sub.2 H.sub.5).sub.3                                                           benzene                                                                            ethanol                                                                            lithium                                                                           solvent                                                                           "   Ho(OC.sub.2 H.sub.5).sub.3                                                           90.1                                                                              24.0                                                                             5.0                                                                              16.0                                                                             24.0                                                                             4.8                                                                              16.6                 [13.5] (0.03)                                                                          (50) (10) (0.09)                                                                            re-     [8.1]                                                                 fluxing                                             31 Er(OCOC.sub.2 H.sub.5).sub.3                                                           benzene                                                                            ethanol                                                                            lithium                                                                           solvent                                                                           "   Er(OC.sub.2 H.sub.5).sub.3                                                           95.3                                                                              23.8                                                                             5.0                                                                              15.9                                                                             23.3                                                                             4.9                                                                              16.1                 [13.6] (0.03)                                                                          (50) (10) (0.09)                                                                            re-     [8.6]                                                                 fluxing                                             32 Tm(OCOC.sub.2 H.sub.5).sub.3                                                           benzene                                                                            ethanol                                                                            lithium                                                                           solvent                                                                           "   Tm(OC.sub.2 H.sub.5).sub.3                                                           91.9                                                                              23.7                                                                             4.9                                                                              15.8                                                                             24.0                                                                             5.1                                                                              16.3                 [13.6] (0.03)                                                                          (50) (10) (0.09)                                                                            re-     [8.4]                                                                 fluxing                                             33 Yb(OCOC.sub.2 H.sub.5).sub.3                                                           benzene                                                                            ethanol                                                                            lithium                                                                           solvent                                                                           "   Yb(OC.sub.2 H.sub.5).sub.3                                                           96.0                                                                              23.4                                                                             4.9                                                                              15.6                                                                             24.4                                                                             5.0                                                                              16.1                 [13.7] (0.03)                                                                          (50) (10) (0.09)                                                                            re-     [8.9]                                                                 fluxing                                             34 Lu(OCOC.sub.2 H.sub.5).sub.3                                                           benzene                                                                            ethanol                                                                            lithium                                                                           solvent                                                                           "   Lu(OC.sub.2 H.sub.5).sub.3                                                           91.1                                                                              23.2                                                                             4.8                                                                              15.5                                                                             24.0                                                                             5.0                                                                              15.5                 [13.8] (0.03)                                                                          (50) (10) (0.09)                                                                            re-     [8.5]                                                                 fluxing                                             35 scandium toluene                                                                            isopropyl                                                                          sodium                                                                            80  2   Sc(O--i-C.sub.3 H.sub.7).sub.3                                                       92.3                                                                              48.6                                                                             9.5                                                                              21.6                                                                             47.1                                                                             9.9                                                                              20.9                 acetate  (50) alcohol                                                                            (0.09)      [6.1]                                          Sc(OCOCH.sub.3).sub.3                                                                       (10)                                                            [6.7] (0.03)                                                               36 La(OCOCH.sub.3).sub.3                                                                  toluene                                                                            isopropyl                                                                          sodium                                                                            "   "   La(O--i-C.sub.3 H.sub.7).sub.3                                                       94.6                                                                              34.2                                                                             6.6                                                                              15.2                                                                             34.0                                                                             6.7                                                                              14.8                 [9.5]    (50) alcohol                                                                            (0.09)      [9.0]                                                        (10)                                                         37 Ce(OCOCH.sub.3).sub.3                                                                  toluene                                                                            ispropyl                                                                           sodium                                                                            "   "   Ce(O--i-C.sub.3 H.sub.7).sub.3                                                       90.6                                                                              34.1                                                                             6.6                                                                              15.1                                                                             33.4                                                                             6.7                                                                              15.4                 [9.5]    (50) alcohol                                                                            (0.09)      [8.6]                                                        (10)                                                         38 Pr(OCOCH.sub.3).sub.3                                                                  toleune                                                                            isopropyl                                                                          sodium                                                                            "   "   Pr(O--i-C.sub.3 H.sub.7).sub.3                                                       93.9                                                                              34.0                                                                             6.6                                                                              15.1                                                                             34.4                                                                             6.9                                                                              16.0                 [9.5]    (50) alocohol                                                                           (0.9)       [9.0]                                                        (10)                                                         39 Nd(OCOCH.sub.3).sub.3                                                                  toluene                                                                            isopropyl                                                                          sodium                                                                            "   "   Nd(O--i-C.sub.3 H.sub.7).sub.3                                                       91.0                                                                              33.6                                                                             6.5                                                                              14.9                                                                             34.0                                                                             6.6                                                                              15.2                 [9.6]    (50) alcohol                                                                            (90)        [8.8]                                                        (10)                                                         40 Sm(OCOCH.sub.3).sub.3                                                                  toluene                                                                            isopropyl                                                                          sodium                                                                            "   "   Sm(O--i-C.sub.3 H.sub.7).sub.3                                                       95.2                                                                              33.0                                                                             6.4                                                                              14.7                                                                             34.1                                                                             6.7                                                                              15.0                 [9.8]    (50) alcohol                                                                            (90)        [9.4]                                                        (10)                                                         41 EU(OCOCH.sub.3).sub.3                                                                  toluene                                                                            Isopropyl                                                                          Sodium                                                                            "   "   EU(O--i-C.sub.3 H.sub.7).sub.3                                                       90.0                                                                              32.8                                                                             6.4                                                                              14.6                                                                             32.1                                                                             6.6                                                                              15.1                 [9.9]    (50) alcohol                                                                            (90)        [8.8]                                                        (10)                                                         42 GD(OCOCH.sub.3).sub.3                                                                  toluene                                                                            isopropyl                                                                          Sodium                                                                            "   "   Gd(O--i-C.sub.3 H.sub.7).sub.3                                                       94.4                                                                              32.3                                                                             6.3                                                                              14.4                                                                             32.0                                                                             6.0                                                                              14.8                 [10.0]   (50) alcohol                                                                            (90)        [9.4]                                                        (10)                                                         43 Td(OCOCH.sub.3).sub.3                                                                  toluene                                                                            isopropyl                                                                          sodium                                                                            "   "   Td(O--i-C.sub.3 H.sub.7).sub.3                                                       91.8                                                                              32.2                                                                             6.3                                                                              14.3                                                                             32.1                                                                             6.4                                                                              14.6                 [10.1]   (50) alcohol                                                                            (90)        [9.3]                                                        (10)                                                         44 Dy(OCOCH.sub.3).sub.3                                                                  toluene                                                                            isopropyl                                                                          sodium                                                                            "   "   Dy(O--i-C.sub.3 H.sub.7).sub.3                                                       94.4                                                                              31.8                                                                             6.2                                                                              14.1                                                                             31.1                                                                             6.2                                                                              14.8                 [10.2]   (50) alcohol                                                                            (90)        [9.6]                                                        (10)                                                         45 Ho(OCOCH.sub.3).sub.3                                                                  toluene                                                                            isopropyl                                                                          sodium                                                                            "   "   Ho(O--i-C.sub.3 H.sub.7).sub.3                                                       92.3                                                                              31.6                                                                             6.1                                                                              14.0                                                                             32.2                                                                             6.6                                                                              14.4                 [10.3]   (50) alcohol                                                                            (90)        [9.5]                                                        (10)                                                         46 Er(OCOCH.sub.3).sub.3                                                                  toluene                                                                            isopropyl                                                                          sodium                                                                            "   "   Er(O--i-C.sub.3 H.sub.7).sub.3                                                       94.7                                                                              31.4                                                                             6.1                                                                              13.9                                                                             31.0                                                                             6.3                                                                              14.2                 [10.3]   (50) alcohol                                                                            (0.09)      [9.8]                                                        (10)                                                         47 Tm(OCOCH.sub.3).sub.3                                                                  toluene                                                                            isopropyl                                                                          sodium                                                                            "   "   Tm(O--i-C.sub.3 H.sub.7).sub.3                                                       91.2                                                                              31.2                                                                             6.1                                                                              13.9                                                                             32.0                                                                             6.3                                                                              14.0                 [10.4]   (50) alcohol                                                                            (0.09)      [9.5]                                                        (10)                                                         48 Yb(OCOCH.sub.3).sub.3                                                                  toluene                                                                            isopropyl                                                                          sodium                                                                            "   "   Yb(O--i-C.sub.3 H.sub.7).sub.3                                                       94.8                                                                              30.9                                                                             6.0                                                                              13.7                                                                             30.1                                                                             6.0                                                                              13.9                 [10.5]   (50) alcohol                                                                            (0.09)      [9.9]                                                        (10)                                                         49 Lu(OCOCH.sub.3).sub.3                                                                  toluene                                                                            isopropyl                                                                          sodium                                                                            "   "   Lu(O--i-C.sub.3 H.sub.7).sub.3                                                       92.0                                                                              30.7                                                                             6.0                                                                              13.6                                                                             30.2                                                                             6.4                                                                              14.2                 [10.6]   (50) alcohol                                                                            (0.09)      [9.7]                                                        (10)                                                         50 Y(OCOCH.sub.3).sub.3                                                                   none n-octyl                                                                            lithium                                                                           "   "   Y(O--n-C.sub.8 H.sub.17).sub.3                                                       95.3                                                                              60.5                                                                             10.7                                                                             10.1                                                                             61.4                                                                             10.9                                                                             10.0                 [8.0]         alcohol                                                                            (0.09)      [13.6]                                                       (70)                                                         51 Sm(OCOCH.sub.3).sub.3                                                                  "    n-octyl                                                                            lithium                                                                           solvent                                                                           "   Sm(O--n-C.sub.8 H.sub.17).sub.3                                                      91.1                                                                              53.6                                                                             9.5                                                                              8.9                                                                              54.2                                                                             10.0                                                                             8.8                  [9.8]         alcohol                                                                            (0.09)                                                                            re-     [14.7]                                                       (70)     fluxing                                             52 Dy(OCOCH.sub.3).sub.3                                                                  "    n-octyl                                                                            lithium                                                                           solvent                                                                           3   Dy(O--n-C.sub.8 H.sub.17).sub.3                                                      91.1                                                                              52.4                                                                             9.3                                                                              8.7                                                                              52.6                                                                             9.8                                                                              8.4                  [10.2]        alcohol                                                                            (0.09)                                                                            re-     [15.0]                                                       (70)     fluxing                                             53 Yb(OCOCH.sub.3).sub.3                                                                  "    n-octyl                                                                            lithium                                                                           solvent                                                                           "   Yb(O--n-C.sub.8 H.sub.17).sub.3                                                      91.3                                                                              51.4                                                                             9.1                                                                              8.6                                                                              51.1                                                                             9.0                                                                              8.8                  [10.5]        alcohol                                                                            (0.09)                                                                            re-     [15.3]                                                       (70)     fluxing                                             54 Y(OCOCH.sub.3).sub. 3                                                                  benzene                                                                            ethanol                                                                            potas-                                                                            solvent                                                                           1   Y(O--C.sub.2 H.sub.5).sub.3                                                          97.5                                                                              32.2                                                                             6.7                                                                              21.4                                                                             32.5                                                                             6.8                                                                              21.1                 [8.0]    (50) (10) (sium)                                                                            re-     [6.6]                                                             (0.9)                                                                             fluxing                                             55 Y(OCOCH.sub.3).sub.3                                                                   xylene                                                                             tert-                                                                              sodium                                                                            80  1.5 Y(O--t-C.sub.4 H.sub.9).sub.3                                                        96.0                                                                              46.8                                                                             8.9                                                                              15.6                                                                             46.4                                                                             8.8                                                                              15.4                 [8.0]    (60) butanol                                                                            (0.09)      [8.9]                                                        (10)                                                         __________________________________________________________________________

COMPARATIVE EXAMPLE 1 (according to the prior art process described inthe aforesaid "Inorg. Chem." Vol. 5(3).)

Lithium isopropoxide (24.3 g, 0.37 mol.) and isopropyl alcohol (150 ml)were placed in a round-bottomed flask of a 300 ml-capacity, to which wasthen added dropwise a solution of anhydrous yttrium trichloride (23.4 g,0.12 mol.) in 25 ml of tetrahydrofuran under stirring. After theaddition of the yttrium trichloride, the mixture in the flask wasstirred at 45° C. for 3 hours with heating by means of a mantle heater,followed by concentration of the reaction solution to dryness byevaporation of the solvent. The residue obtained was admixed with 150 mlof benzene and the resultant solution was filtered to remove theinsoluble matter. Distillation off of the benzene from the filteredsolution gave 16.8 g of yttrium isopropoxide as a slightly yellowcrystal. Yield 52.6%

COMPARATIVE EXAMPLES 2-16

The process of Comparative Example 1 was repeated using such differentanhydrous rare earth metal trichlorides and such different alkali metalalkoxides as indicated in Table 3 below. The test results obtained aretabulated in Table 3.

                                      TABLE 3                                     __________________________________________________________________________                           Reaction time                                          Com-           Alkali metal                                                                          (heating &                                             parative                                                                            Rare earth metal                                                                       alkoxide                                                                              stirring)                                                                            Products Yield                                  Ex.   chloride (mol.)                                                                        (mol.)  (hrs.) (g)      (%)                                    __________________________________________________________________________    2     ScCl.sub.3                                                                             NaOCH.sub.3                                                                           3      Sc(OCH.sub.3).sub.3                                                                    42.3                                         (18.2) [0.12]                                                                          (0.37)         (7.0)                                           3     LaCl.sub.3                                                                             NaO--i-C.sub.3 H.sub.7                                                                "      La(O--i-C.sub.3 H.sub.7).sub.3                                                         50.3                                         (29.4) [0.12]                                                                          (0.37)         (17.3)                                          4     CeCl.sub.3                                                                             KOC.sub.2 H.sub.5                                                                     "      Ce(OC.sub.2 H.sub.5).sub.3                                                             56.4                                         (29.6) [0.12]                                                                          (0.37)         (18.6)                                          5     PrCl.sub.3                                                                             KO--i-C.sub.3 H.sub.5                                                                 "      Pr(O--i-C.sub.3 H.sub.7).sub.3                                                         40.5                                         (29.7) [0.12]                                                                          (0.37)         (14.0)                                          6     NdCl.sub.3                                                                             LiO--i-C.sub.3 H.sub.7                                                                2      Nd(O--i-C.sub.3 H.sub.7).sub.3                                                         48.9                                         (30.1) [0.12]                                                                          (0.37)         (17.1)                                          7     SmCl.sub.3                                                                             LiO--n-C.sub.8 H.sub.17                                                               "      Sm(O--n-C.sub.8 H.sub.17).sub.3                                                        33.1                                         (30.8) [0.12]                                                                          (0.37)         (21.3)                                          8     EuCl.sub.3                                                                             NaO--n-C.sub.6 H.sub.13                                                               "      Eu(O--n-C.sub.6 H.sub.13).sub.3                                                        41.0                                         (31.0) [0.12]                                                                          (0.37)         (22.4)                                          9     GdCl.sub.3                                                                             NaO--i-C.sub.3 H.sub.7                                                                3      Gd(O--i-C.sub.3 H.sub.7).sub.3                                                         56.4                                         (31.6) [0.12]                                                                          (0.37)         (20.6)                                          10    TbCl.sub.3                                                                             KO--t-C.sub.4 H.sub.9                                                                 2      Tb(O--t-C.sub.4 H.sub.9).sub.3                                                         39.4                                         (31.8) [0.12]                                                                          (0.37)         (17.9)                                          11    DyCl.sub.3                                                                             KO--n-C.sub.3 H.sub.7                                                                 "      Dy(O--n-C.sub.3 H.sub.7).sub.3                                                         49.2                                         (32.3) [0.12]                                                                          (0.37)         (18.3)                                          12    HoCl.sub.3                                                                             LiO--n-C.sub.4 H.sub.9                                                                3      Ho(O--n-C.sub.4 H.sub.9).sub.3                                                         57.1                                         (32.6) [0.12]                                                                          (0.37)         (26.3)                                          13    ErCl.sub.3                                                                             LiO--i-C.sub.3 H.sub.7                                                                3      Er(O--i-C.sub.3 H.sub.7).sub.3                                                         50.5                                         (32.8) [0.12]                                                                          (0.37)         (19.0)                                          14    TmCl.sub.3                                                                             KO--n-C.sub.4 H.sub.9                                                                 2      Tm(O--n-C.sub.4 H.sub.9).sub.3                                                         47.9                                         (33.0) [0.12]                                                                          (0.37)         (22.3)                                          15    YbCl.sub.3                                                                             KO--n-C.sub.3 H.sub.7                                                                 3      Yb(O--i-C.sub.3 H.sub.7).sub.3                                                         51.8                                         (33.5) [0.12]                                                                          (0.37)         (19.9)                                          16    LuCl.sub.3                                                                             NaOC.sub.2 H.sub. 5                                                                   "      Lu(OC.sub.2 H.sub.5).sub.3                                                             55.1                                         (33.8) [0.12]                                                                          (0.37)         (20.5)                                          __________________________________________________________________________

COMPARATIVE EXAMPLE 17 (according to the prior art process described inthe aforesaid "Zeit. Anorg. All. Chemie" pp. 67-71, 325(12) (1963))

Methanol (150 ml) and anhydrous scandium trichloride (ScCl₃, 6.1 g, 0.04mol.) were placed in a round-bottomed flask of a 300 ml-capacity andsubsequently heated under refluxing for 3 hours. After the reaction wascompleted, a stream of dry ammonia gas (0.12 mol.) was passed into thereaction solution in said flask, followed by heating for 1 hour underrefluxing. The reaction solution was then filtered to remove thedeposited, bulky crystals (comprising the scandium methoxide as formed).The crystalline product so collected was washed well with hot methanolto remove the by-formed ammonium chloride therefrom, affording 3.1 g ofscandium methoxide as slightly yellow colored crystals.

Yield 56.3%.

What we claim is:
 1. A process for the production of a rare earth metalalkoxide of the general formula

    M(OR).sub.3                                                (I)

wherein M denotes a rare earth metal atom and R denotes an alkyl group,which comprises reacting a rare earth metal carboxylate represented bythe general formula

    M.sub.n X.sub.3                                            (II)

wherein M is as defined above, X denotes the residue of a carboxylicacid and n is an integer of 1 or 2, provided that n is 1 when X denotesthe residue of a mono-carboxylic acid; and n is 2 when X denotes theresidue of a di-carboxylic acid, with an alkali metal alkoxiderepresented by the general formula

    ROM'                                                       (III)

wherein R is an alkyl group as defined above and M' denotes an alkalimetal, in an inert organic solvent or liquid under the anhydrousconditions.
 2. A process as claimed in claim 1 in which the rare earthmetal carboxylate used is of the formula

    M(OCOR.sup.a).sub.3

wherein M denotes a rare earth metal and R^(a) denotes a hydrogen atomor an alkyl group of 1 to 10 carbon atoms or an optionally substitutedaryl group.
 3. A process as claimed in claim 1 in which the rare earthmetal carboxylate used is of the formula ##STR10## wherein M denotes arare earth metal and R^(b) denotes a chemical linkage bond or analkylene group of 1-4 carbon atoms or phenyl group.
 4. A process asclaimed in claim 1 in which the rare earth metal carboxylate used isselected from the formate, acetate, propionate, benzoate and oxalate ofthe rare earth metal.
 5. A process as claimed in claim 1 in which theinert organic solvent used as the reaction medium is selected fromalkanols of 1 to 10 carbon atoms.
 6. A process as claimed in claim 1 inwhich the inert organic solvent as the reaction medium is selected frombenzene, toluene and xylene as aromatic hydrocarbons.
 7. A process asclaimed in claim 1 in which the inert organic solvent as the reactionmedium is a mixture of benzene, toluene or xylene with an alkanol of 1to 10 carbon atoms.
 8. A process as claimed in claim 1 in which thereaction is conducted for a time of 1 to 3 hours at a temperature ofranging from ambient temperature to the refluxing temperature of thereaction medium.
 9. A process as claimed in claim 1 in which the alkalimetal alkoxide is such one that has been produced in situ in thesolution of the rare earth metal carboxylate in an alkanol by reacting ametallic alkali metal with the solvent alkanol of said solution of therare earth metal carboxylate.
 10. A process as claimed in claim 1 inwhich the reaction mixture after completion of the reaction isconcentrated to dryness, the solid residue is then re-dissolved in avolume of benzene, toluene or xylene, the solution so obtained isfiltered to remove the insoluble solids therefrom and to afford a clearsolution of the rare earth metal alkoxide in benzene, toluene or xylene.